Seeding grasses with alfalfa in pastures

Seeding grass with alfalfa can boost yield and drying rate while keeping animals healthy. 

Reasons to seed grass with alfalfa

Yield

Yield is the largest driver of profit in stored forage production. Alfalfa-grass mixes often yield more than pure alfalfa. With high fixed harvest costs, each cutting must produce a bountiful harvest.

• A small grain or Italian/annual ryegrass companion crop with a spring seeding provides greater seeding-year yield than alfalfa seeded directly.
• Sod-forming grasses like reed canarygrass or smooth bromegrass allow traffic when fields are wetter. They also speed drying times, which reduces possible weather-related losses.
• Orchardgrass and tall fescue have good fall growth that allows a useful fall harvest or grazing. These grasses also provide more residue than alfalfa stubble. Residue catches snow and insulates alfalfa crowns.

Drying rate

Grasses with stems present speed up the swath drying rate. Some grasses produce stems with every growth cycle and create fluffy swaths that dry faster. These grasses include:

• Reed canarygrass
• Smooth bromegrass
• Timothy create

Some leafy grasses with shiny surfaces, such as tall fescue and ryegrasses, won’t speed the drying rate.

Persistence

• Grasses catch snow and insulate better than alfalfa alone.
• Grasses better protect alfalfa from winter injury.
• Winter-hardy grasses provide insurance if the alfalfa winter kills.

Feeding value

• At like growth stages, grass has higher neutral detergent fiber (NDF) than alfalfa. But grass has much higher NDF digestibility. NDF digestibility reflects the feed’s energy value.

• Many dairies feed straw for fiber. Forage grasses provide fiber in a more digestible form.

• Grass-alfalfa mixes are less likely to cause bloat than pure alfalfa when grazed.

The relative feed value (RFV) index is good for alfalfa quality but tends to undervalue grass feeding values. The new relative forage quality (RFQ) index:

• Better reflects higher fiber digestibility in grasses.
• Shows how feeding grass impacts energy and intake potential.

Weed and erosion control

• Weeds show up in perennial forages if bare soil is present for too long.
• Some grasses help to quickly cover soil during the seeding year.
• Many grasses also provide long-term cover, particularly if the grass is a sod-former or if you broadcast seed.
• Small-grain companion crops can control erosion.

Managing alfalfa-grass mixes

Proper management of alfalfa-grass mixes can ensure the crop will be profitable.

Short rotations

Keep alfalfa stands for three to four years for the most profit. This allows you to maximize yield potential and benefit from alfalfa’s nitrogen in crop rotations. Short rotations may be good for grasses with less long-term persistence but high yield and quality, including tall fescue, festulolium, and perennial ryegrass.

Seeding rates

Seed enough grass to have a good mix, but avoid overseeding competitive grasses. How often you cut and your cutting height can affect alfalfa-grass ratios. For example, cutting shorter and less often lowers the percentage of orchardgrass.

Seeding methods

Broadcast seeding is likely the best method for seeding alfalfa-grass mixes. This is especially true when using bunch grasses to provide more even cover.

• Broadcast perennial forages.

• Use a drill to seed a small grain or Italian/annual ryegrass companion crop.

• Avoid seeding alfalfa in the same row as competitive grasses.

Seeding timing

Since alfalfa-grass mixtures have few herbicide options, August may be the best time to seed if soil moisture is ideal. There’s less weed competition during late summer than in spring.

Swath width

Wide swaths speed drying and reduce the risk of weather-related losses, especially with leafy grasses.

Fertility

Good potassium levels are key to growing alfalfa with competitive grasses. Grass takes up soil potassium better than alfalfa.

Manure is a great fertility source when you apply it before seeding or right after cutting.